1. Technical Field
The present invention relates to magnetoresistive transducers. More particularly, the present invention relates to improved conductors for dual stripe magnetoresistive transducers.
2. Description of the Prior Art
Continuing advances in magnetic media technology allow increasing data storage densities. One active area of development is that of reading transducers. As such transducers are made smaller, data densities are increased. Magnetoresistive (MR) thin film technology has provided a particularly promising area of inquiry with regard to producing smaller reading transducers. In such technology, conductive thin films are formed on a substrate using techniques analogous to those of the semiconductor arts. Dual stripe MR transducers, such as are described in U.S. Pat. No. 3,860,965, issued to Voegeli, reflect the current state of the art.
The magnetic properties of ferromagnetic thin films used to produce MR transducers can be strongly influenced by the topographical features present on a transducer substrate. See, for example, Effect of Surface Rouqhness on Magnetic Properties of Films, Prosen et al, J. App. Phys., Vol. 34, No. 4 (1963); and Magnetic Properties of Ni-Fe Films Prepared by a DC Triode Sputtering Method, Minakata, IEEE Transactions on Magnetics, Vol. 24, No. 3 (1988). In particular, soft magnetic properties are affected when the height of such features is on the same order or greater than the thickness of the films, and such features have angles of departure from a substrate plane that are greater than a critical angle. The primary consequences of these sorts of features are local variations in anisotropy caused by magnetostriction, and local variations in film thickness caused by shadowing or angle of incidence considerations.
These non-uniformities serve as magnetic domain nucleation sites in ferromagnetic films. When present in magnetoresistive (MR) films such as are used to produce MR transducers, these magnetic domains transform a smoothly varying transducer output corresponding to resistance versus applied field into a sequence of irreproducible jumps associated with sudden movement of domain walls. Thus, an unacceptable level of noise, referred to as Barkhausen noise, is produced which degrades transducer performance. At track densities currently envisioned, there needs to be an improvement in the signal-to-noise ratio of MR transducers, as well as a mechanism for reducing and/or eliminating critical errors related to Barkhausen noise.